More than two years after the tsunami that caused the Fukushima Daiichi nuclear disaster in Japan, heavy rains have brought on soaring radiation levels in groundwater under the nuclear plant, according to the Tokyo Electric Power Co. And at the beginning of October, scientists testing 50 migratory bluefin tuna caught off the California coast found that 33 were contaminated with radioactive cesium-134, attributing the contamination to the Fukushima accident.

News reports in West Coast publications have sounded the alarm to worried diners, but some of the nation's top experts on food safety say there is no cause for panic.

First and foremost, says Steve Otwell, seafood specialist with Florida Sea Grant, a research partnership between the National Oceanic and Atmospheric Administration and Florida universities, very few bluefin tuna from near Japan reach U.S. markets.

"In fact, there are few seafood shipments from Japan to the United States. They retain most of their catch and import from other nations and areas."

Katie Sosa, vice president of sales for Sammy's Seafood in St. Petersburg, estimates that 70 percent of the tuna she imports comes from Latin America (Costa Rica, Panama and Trinidad), and 30 percent is domestic, largely from Louisiana and Boston.

"We started this year knowing that after that tsunami we'd feel the effects because Japan is a huge market. They buy our domestic tuna from Boston, wrap it in bamboo and ship it home. Japan has encroached into other markets, as has China, to tell the truth."

Still, Sosa says she hasn't seen significant price hikes, although tuna sizes have shrunk as the species has been overfished.

Because diners seldom know with any certainty the provenance of the food in front of them, should restaurantgoers still be leery?

According to Timothy J. Jorgensen, the director of the Health Physics and Radiation Protection Program in the Department of Radiation Medicine at Georgetown University, even Pacific tuna pose no threat.

"By the time the tuna migrate across the ocean, the levels of any radioactivity that they may have picked up in Fukushima coastal waters are well below natural background radioactivity levels."

Gavin Gibbons, director of media relations for the National Fisheries Institute in McLean, Va., says, "You may be able to find some activist-types who are willing to ignore the science and the regulatory perspective provided by agencies like FDA and NOAA and say there are concerns. But the fact is commercial seafood presents no genuine health concerns for consumers. Your average banana in the grocery store emits more radiation than fish tested off the West Coast."

If cesium-134 levels in Pacific migratory tuna soar along with those in groundwater under Fukushima, Jorgensen still doesn't fear for consumers' safety. He says that because there are no measurable health effects from the natural radioactivity in our food (foods such as bananas, nuts and fish), there can be no measurable health effects from the reactor radioactivity, which is hundreds to thousands of times less than the natural radioactivity in the fish.